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J R Soc Med. 1981 August; 74(8): 595–600.
PMCID: PMC1438905

Oxygen tension measurement using an automatic blood gas analyser1


Two different methods of assessing the reliability of the oxygen electrode of one model of an automatic blood gas analyser (BGA) have been studied. In the first, a single automatic BGA was assessed by using outdated bank blood which was pumped around a small extracorporeal circuit into which known gas mixtures were passed. Oxygen tension was varied between 2 and 16 kPa. In the second, fresh heparinized blood was tonometered with calibrated gases and submitted to the automatic BGA used in the first part of the study and also to three other identical machines. Each of the machines was between 3 and 4 years old.

Eighteen different units of blood were used in the first part of the study. The correlation coefficient between the automatic BGA and the Po2 in the extracorporeal circuit varied between 0.29 and 0.99. 31% of the total of 209 measurements made by the automatic BGA were more than 1.2 kPa from the reference value, 25% of them being between 1.2 and 4.0 kPa from the reference value. In the second part of the study, the correlation coefficient between this automatic BGA and the tonometered blood was 0.96. The correlation coefficients for the 3 other identical BGAs were 0.84, 0.97 and 0.88, indicating that the BGA used in the first part of the study was no worse than any of the others.

It is suggested that although clinicians are likely to ignore readings of an automatic BGA that are more than 4.0 kPa from the true value and are likely to repeat the investigation, readings between 1.2 and 4.0 kPa from the true value may adversely affect patient management.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.
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  • McSweeney FM, Bullock DG, Gregory A, Whitehead TP. An interlaboratory survey of hydrogen ion and blood gas determinations. Ann Clin Biochem. 1979 Sep;16(5):249–253. [PubMed]
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  • Rubin P, Bradbury S, Prowse K. Comparative study of automatic blood-gas analysers and their use in analysing arterial and capillary samples. Br Med J. 1979 Jan 20;1(6157):156–158. [PMC free article] [PubMed]
  • Selman BJ, Tait AR. Towards blood-gas autoanalysis an evaluation of the radiometer ABL. Br J Anaesth. 1976 May;48(5):487–494. [PubMed]

Articles from Journal of the Royal Society of Medicine are provided here courtesy of Royal Society of Medicine Press